Tension and releasing means for sewing machines

ABSTRACT

The present sewing thread tension and releasing attachments are attachable to a sewing machine and operate to normally maintain a tension on the thread being fed to sewing machine needle by passing the thread between a pair of discs resiliently held together and at times pneumatic means are operated to separate said discs to release the thread whereupon further pneumatic means pull the thread towards the needle to permit the severing of the thread from a work piece.

UnitedStates Patent Robert F. Miller Camp Hill; Roy E. Miller,Mechanicsburg, Pa. 856,965 Sept. 1 1, 1969 Feb. 23, 1971 The ReeceCorporation Waltharn, Mass. Continuation-impart of application Ser. No.

432,721, Feb. 15, 1965, now Patent No. 3,360,002.

Inventors Appl. No. Filed Patented Assignee TENSION AND RELEASING MEANSFOR SEWING MACHINES 3 Claims, 21 Drawing Figs.

U.S. Cl 112/255, 242/150 Int. Cl D05!) 47/00 Field of Search 112/255,254, 245; 242/150 [56] References Cited UNIT ED STATES PATENTS 2,610,8139/1952 Campbell 242/150 2,646,944 7/1953 Heffelfinger 242/150 3,364,8891/1968 Wiener 112/245 Primary Examiner-Patrick D. Lawson AssistantExaminer-George l-l. Krizmanich Attorney-Linton & Linton ABSTRACT: Thepresent sewing thread tension and releasing attachments are attachableto a sewing machine and operate to normally maintain a tension on thethread being fed to sewing machine needle by passing the thread betweena pair of discs resiliently held together and at times pneumatic meansare operated to separate said discs to release the thread whereuponfurther pneumatic means pull the thread towards the needle to permit thesevering of the thread from a work piece.

TENSION AND RELEASHWG MEANS FOR SEWING MACHINES The present invention isa continuation-in-part of applicants copending application Ser. No.432,721, filed Feb. 15, I965, now U.S. Pat. No. 3,360,002.

The present invention is concerned with an improvement in sewingmachines and more particularly is directed to apparatus forautomatically controlling the operation of the sewing machine andsevering the sewing thread.

The principal object of the present invention is toprovide a apparatusattachable to conventional sewing machines which apparatus while underthe control of an operator, will automatically position the needle,raise and lower the presser foot, properly tension the sewing thread,and sever said sewing thread and including a control for starting,speeding up, slowing down or stopping the operation of the sewingmachine.

A further important object of the invention is to provide means of formodifying conventional sewing machines by the addition of reliableequipment which results in faster and simpler sewing operations andautomatically positions the sewing needle and cuts the thread giving theoperator the choice of putting many stitches or one single stitch in ata time into the work piece before automatically severing the threadtherefrom.

Another important object is to provide means for automaticallypositioning the needle bar with the needle at its top position or at itslowermost position and with'means for stopping the sewing machine whenthe needle is in its up position breaking an electrical. circuitconnected to said positioning means whereupon the operator can energizesaid electrical circuit for down positioning said needle bar and liftingthe presser foot allowing the operator to turn the work piece around theneedle.

A further object of the invention is to provide means for automaticallyand properly cutting thesewing thread between the thread handling systemand the work piece when each sewing step of the work piece is completed.Further objects of the invention will be in part obvious and in partpointed out in the following detailed description of the accompanyingdrawings in which:

FIG. I is a front perspective view of a conventional sewing machine withthe apparatus of the present invention connected thereto.

FIG. 2 is an enlarged perspective view of the needle bar carrying end ofa sewing machine ann modified according to the present invention.

FIG. 3 is an enlarged front elevation of a part of a sewing machine inaccordance with the present inventiorrwith elements removed to show thesewing machine drive.

FIG. 4 is an end view taken from the right of FIG. 3.

FIG. 5 is an enlarged sectional view taken on line 5-5 of FIG. 3.

FIG. 6 is a cross-sectional view taken on line 6-6 of FIG. 3

and laterally of the sewing machine bed showing the positioning cylinderof the present apparams.

FIG. 7 is a greatly enlarged detail view of the needle positioningcontrol with its cap removed.

FIG. 7a is an exploded perspective view of the synchronizer valvebracket and roller and handwheel.

FIG. 8 is a greatly enlarged cross-sectional view taken on line 8-8 ofFIG. 6.

FIG. 9 is an end view of the slip clutch partially shown in FIG. 8.

FIG. 10 is an enlarged top view of the sewing thread cutoff.

FIG. 11 is a cross-sectional view taken on line 11-11 of FIG. 11.

FIG. 12 is a cross-sectional view taken on line 12-12 of FIG.

FIG. I is an end view of the thread cutoff tubes. FIG. 13 is a greatlyenlarged sectional view taken on line 13-13 of FIG. 2.

FIG. 14 is a schematic diagram of the pneumatic and electrical system ofthe present apparatus.

FIG. IS-is a partial cross-sectional view taken on line 15-15 of FIG. 4showing the rear of the sewing machine and the presser foot controls.

FIG. 16 is a wiring diagram of the apparatuswhen the needle is up andpresser foot raised.

FIG. 17 is a wiring diagram of the apparatus when the needle is down.

FIG. 18 is an enlarged view of the knee switch forming part of thepresent apparatus. Referring now more particularly to the accompanyingdrawings in which like and corresponding parts are designated by similarreference characters, LA and LB designate right and standard legs and LCand LD the left hand standard legs. E is a rod extending between andconnected to said standards. with a treadle F having a tube G rotatablymounted on rod E. H is a sewing machine bed supported by said standardswhilel is an upright mounted on said bed and having crossarm Jsupporting rod K on which is rotatably mounted a spool L of thread M.Guide arm N is also mounted on upright I and has eye 0 through-whichthread Mi passes to pin P on the cantilever arm R of a conventionalsewing machine generally designated Q. Said sewing machine slideablysupports needle bar S with needle T and presser foot U.

Said sewing. machine hasia drive shaft hand wheel V around which extendsdrive belt W. X is the bed plate of the sewing machine and AA a bobbin.

The above elements A to- AA inclusive are conventional structures forsewing machines and supporting structure therefor.

Link I is pivotally connected at one end to bearing 2 carried by treadleF and pivotally connected by stub axle 3 to one end of a second link 4.1

Link 4 has an arm 5 fixedly connected thereto and a bent end 6 while arm5 is pivotally connected by'pin7 to the piston rod 8 of a pneumaticbrakecylinder 9 to which is attached a solenoid valve l0. Arm I1 isfixedly connected at one end to brake cylinder 9 and pivotally connectedby pins 13 to the control yoke 13a of a combination electric motor,clutch and brake l4. Said electric motor, clutch and brake 14 may, forexample, be a Singer Electric Transmitter series 552 or 553 produced byThe Singer Manufacturing Company, Elizabethport F, New Jersey;

Said motor, clutch and brake l4 hereinafter referred to as atransmitter, is adjustably fastened to the bottom of bed H by anyconventional means such as bolts or the like (not shown). A finger l2fixedly mounted on said member 14 pivotally supports arm 11 and theother bent end of link 4 by means of a stub axle 12a.

Said transmitter 14 has a slideable drive shaft 14a extending therefromthrough control yoke 13apivotally connected by pins 13 to arm 11. Axialmovement of yoke 13a axially moves drive shaft 14a due to stops (notshown) on said drive shaft for engaging or disengaging said drive shaftthrough a mechanism (not shown) in transmitter 14 with the electricmotor through the clutch or brake in transmitter 14.

A pulley I5 is fixedly connected to shaft as is a second pulley 16.Drive belt W extends around pulley 15 while drive belt 17 extends aroundpulley l5.

A plate 18 is fixedly connected to bed H and extends normal thereto.Said plate has a slot 19 through which is adjustably mounted the shaft200 rotatably supporting a pulley 20 by means of a nut (not shown) onsaid pulley shaft on the opposite side of plate 18 to said pulley 16.Further pulleys-21 and 21a are rotatably mounted on plate 18.

Piston rod 23 of pneumatic cylinder 24 has screws 22 around which theends of belt 17 are fastened while said belt extends around pulleys20,21 and 21a. Cylinder 24 has tubes 25 and 26 connected to the endsthereof for the operation of said piston rod.

Brake cylinder 9 has tubes 26 and 27 connected to the ends thereof forthe control of piston rod 8 while solenoid valve 10 has a tube 28 forthe admission of air under pressure into the head of brake cylinder 9 asdetennined by solenoid valve 10.

A pneumatic speed control 29 has an air line tube 30 connected to thebottom thereof while the top is connected to the bottom thereof whilethe top is connected to a presser foot lift cylinder 31 operating apiston rod 31a whose connection to presser foot U will be explainedhereinafter.

An angle rod 32 has a knee plate 34A attached thereto by clamp 34. Saidangle rod is pivotally connected by stub axle 33 to transmitter 14 andis also fixedly connected by welding or the like to cylinder 31 forraising the same.

A microswitch MS l is fixedly mounted on transmitter 14 with its controlpositioned for being pushed by link 4 when the same is raised. A secondmicroswitch MS 2 is carried by link 4 and has its control positioned forbeing pushed against member 14 when link 4 is raised.

A make and break electrical switch 35 for the electrical circuit ishoused in box 36 attached to bed H.

A bobbin winder is shown at 37 in FIG. 4 bearing against belt W.

A cylindrical housing 38 has an extension V of the sewing machine driveshaft rotatably extending through an axial bore of said housing, whilecam 39 therein is fixedly connected to said extension V and thus to handwheel V for rotation therewith. Said cam is circular except for radialpoint 40. A rocker 41 of electrical insulating material is pivotallymounted on pin 42 carried by housing 38 and carries a spring contact 44.A point 45 is fixedly mounted on housing 38 for normally being engagedby contact 44 due to spring 43 connected to housing 38 and rocker 41.

A second insulating rocker 46 is pivotally mounted on pin 47 carried byhousing 38 and said rocker 46 is held against cam 39 by spring 48attached to said rocker and housing 38. Said rocker carries a springcontact 49 normally bearing against point 50 fixedly connected tohousing 38.

Points 45 and 50 are positioned 180 apart and so that cam 39 opens onecontact 44 or 49 from its respective point 45 or 50 when the needle barS is all the way up and the other of said contacts when the needle baris all the way down. A cable 51 is connected to points 45 and 50.

Pulley 16 contains a slip clutch provided by hub 16a keyed by key 54 inslot 55 to shaft 14a and positioned within axial bore 52 of said pulley.A plurality of rollers 53 are positioned between hub 16a and said pulley16 and hub 16a has a series of spaced apart radial teeth 56 and inwardlyslanting curved peripheral portions 57 each extending between a pair ofconsecutive teeth 56 with a roller 53 positioned on each portion 57 forrolling movement between the pair of teeth 56 terminating said portion57. A washer 58 is positioned against the outer end of said hub 16a andsaid pulley 16 while a ring nut 59 in threaded engagement with threads60 on shaft 14a retains washer 58 in place. Hub 16a further has anannular flange 61 which provides a guide for the inner end of saidpulley 16. Thus hub 16a, pulley 16, washer 58 and flange 61 provide acage forrollers 53.

As best shown in FlGS. 2 and 5, the end face 62 of said sewing machinearm R has a recess 63 in which is mounted microswitch 64 alongside apair of microswitches 65 and 65a. Microswitch 64 has an extended controlbar 66 spaced from extended control bars 67 and 67a of microswitches 65and 65a, respectively.

A block 68 is fastened to the end of a piston rod 81 by screws 69 andhas a lateral finger 70 extending between control bar 66 and controlbars 67 and 67a.

Sewing machine arm end 62 has recesses 71 in the back, 72 in the frontand 73 in the bottom leading to recess 63 and a cover plate 74 in FIG.4, for said arm end 62.

A U-shaped guide 75 is mounted on the front of arm end 62 while rollers76, 77, and 78 extend across opening 72.

Pigtails 79 and 80 are connected to block 68 and positioned forextending through opening 72 between rollers 76, 77 and 78.

Said piston rod 81 extends through opening 71 into a pneumatic cylinder82 fastened to the rear side of arm end 62 and which cylinder has a tube82a connected to the inner end thereof, a screw 83 whose threads are inthreaded engagement with cylinder 82 and lock nut 84b with screw 83extending into cylinder 84 for limiting the movement of piston rod 81towards the outer end of said cylinder. A coil spring 85 encirclespiston rod 81 between block 68 and said cylinder.

A pin 86 attached to arm end 62 in opening 73 pivotally supports bentlever 87 extending through said opening 73. A sleeve 88 of a threadclamp is in threaded engagement with ann end 62 and has coil spring 89on the inner end thereof while valve shaped stem 90 slideably extendsthrough said sleeve 88 and coil spring 89 with its flanged inner endagainst arm 87 and retaining coil spring 89 against sleeve 88. Saidsleeve has a valve seat shaped recess 91 in the outer end thereof for attimes receiving the outer end of valve stem 90.

A thread guide 93 attached to arm R has bent spring arms 92 adjustablyheld by bolt 94 in threaded engagement with said arm R.

An automatic thread tension release consists of a cylinder 95, a piston95a in said cylinder, a threaded rod 95b fixedly connected at one end toarm R, a disc 95c slideably mounted on rod 95b, a second disc 95dfixedly connected to arm R, tube 96 connected to the outer end ofcylinder 95, nut 97 in threaded engagement with rod 95b and a coilspring 98 surrounding rod 95b between said nut and the intum end 95c ofsaid cylinder 95. Rod 95b is split at its outer end of for receiving pin95F extending through a slot in the extension of said piston and intocylinder 95 for preventing the turning of said cylinder.

A thread cutoff is best shown in FIGS. 5 and 10 to 12a, inclusive. Saidthread cutoff has a pair of superposed curved tubes 99 and 100 with asteel band 101 extending in tube 99 and a second steel band 102extending in tube 100. Tube 99 has an upturned lip 103 at the free outerend thereof and an opening 104 extending therethrough above the freeouter end of tube 100 and bobbin AA of the sewing machine 0. Saidtube-free ends are positioned just below the needle opening for bed X ofthe sewing machine.

A cylinder head 105 is positioned below a bottom portion 106 of thesewing machine in threaded engagement with a cylinder tube 108. Acylinder cap 107 also is in threaded engagement with cylinder tube 108,but positioned above bottom portion 106 of the sewing machine and hastubes 99 and 100 integral therewith and openings for bands 101 and 102which bands are also integral with piston rod 109, slideable in tube 108and extending through head 105. A coil spring 110 surrounds piston rod109 between head 105 and nut 111 in threaded engagement with said pistonrod. A tube 112 is connected to and through head 105.

As shown in FlG. 10 the sewing machine bottom member 106 has asemicircular recess 116 while a block also has a semicircular recess 113for holding tube 108 therebetween. Bolts 115a and 115!) extend throughblock 115 and screw into bottom member 106 holding said block therein.

Microswitch 117, FIGS. 1 and 18, is mounted on standard leg LC with itscontrol button 117a facing a knee plate 118 pivotally mounted on rod119a pivotally connected by pivot 119 to bed H. Plate 118 has an arm118a attached thereto while rod 119a has a pin 11% extending therefromand collar 1190 with coil spring 119d whose ends engage said plate andcollar.

Plate 118 as shown in FIG. 18 is pivoted inwardly depressing controlbutton 117a and is held in that position by arm 118a engaging pin 11%.An operator by manually pushing said plate can disengage arm 118 frompin 11% whereupon plate 118 will pivot out and move upwardly throughspring 119d releasing control button 1170. Thus plate 118 can be heldagainst control button 117 a whenever the operator requires the same.

A double source of electrical current is indicated by double wall socket120 with plugs .21 and 122 each plugged in one of the sockets. Plug 121is connected to switch 35 while plug 122 is connected to the electricmotor, clutch and brake 14 for energizing the same.

An air tube 123 is connected to a source of air under pressure 9 (notshown) and to and through box 124, FIG. 3, which houses solenoid valvesA, B, C, D and 140 and air speed regulators 125, 126 and 127 and tube128, FIG. 14, connected to said tube 123.

Referring to FIG. showing the back of sewing machine Q, piston rod 310,see FIG. 3, extends through bed H and is loosely connected to lever 129pivoted on arm R by a pin 130. A pair of nuts 131 in threaded engagementwith threads 132 of rod 314 are on each side of lever 129. Said lever129 is pivotally connected by pin 133 to link 134 while link 134 ispivotally connected by pin 135 to the conventional presser foot raisingand lowering lever 136 o of the sewing machine.

Mounted on the top of the sewing machine 0, adjacent to the handwheel Vis a bracket 137, having a downwardly extending leg 138. Secured to saidleg 138, is an air cylinder 139 having a piston rod 141 extendingtherefrom in the direction of the handwheel V. A pin 142 pivotallysupports arm 143 on said bracket so that arm. 143 extends between leg138 and handwheel V. The free end of arm 143 has a roller 144rotatablymounted thereon which is adapted to move into notch 145 on thehandwheel V when said piston rod 141 is extended due to air being forcedinto cylinder 139 through tube 166 which is connected to control valve140. The notch 145 is located in such a position on handwheel V so thatthe needle bar 8 of the sewing machine will be in top dead centerposition when said roller 144 is engaged in notch 145.

Referring to FIG. 7a, notch 145 is in the periphery of a ring 146 heldby set screws 147 on handwheel V modified to receive the same. Housing38 has an extension 148. integral therewith and link 149 attached tosaid extension. One end of spring 150 is attached to link 149 anditsother end to arm'152 while stop 151 extends from extension l48'to arm152 limiting the contraction of spring 150.

Screws 153 extend through openings l54in bracket 137 into the top ofsaid sewing machine for retaining said bracket thereon. Screw 155extends through washer 156 and spring 157 into threaded opening 155a insaid bracket.

The threaded end of cylinder139 has nut 158 and washer 159 thereon andextends into threaded opening 160 in said bracket for being supportedthereby.

Set screw 161 is in threaded opening ,162;for engaging the end of pin142'in opening 174 for retainingsaid pin therein.

Elbow 163 is in threaded engagement with threaded opening 164 incylinder 139 while eyelet 165a and sleeve 165 are in said elbow and nut1640 is in threaded engagement with'said elbow retaining tube 166 tosaid elbow.

Clamp 167 for wire 51 and arm 152 are attachedto bracket leg 138 byscrews 168 passing through openings 169 in arm 152 into threadedopenings 169a inleg 138. Clamp 170 for wire 51 has screw 171 extendingthrough'washer 172, clamp 170 and into threaded opening 172a in arm 152.

Arm 143 has a lateral opening1173 through which extends pin 142 and aroller pin 175 extending through arm openings 176 and roller 144rotatably retaining said roller partially in.

arm recess 174. A retaining ring 177 fits the end of roller pin 175 forholding the same in place.

FIG. 14 is a combination electrical and pneumatic sche matic diagramshowing the electrical as well as compressed air connections between theelements hereinbefore referred to. In

this diagram there is also included relays R and R whose.

operation will be hereinafter described.-

FIG. 16 is a view of the electrical circuit wiring diagram of FIG. 14when needle T is in its up position and presser foot U raised, but withsynchronizer valve 140 omitted. When the operator releases his heelingaction on treadle F, the presser foot U will drop.

FIG. 17 is a view of the electrical circuit wiring diagram of FIG. 14when needle -T is in its down position;

In the operation of a sewing machine Q, modified according to thepresent invention, thread M is passed to post P, through guide Y,between disc 95!: and disc 95d, through thread tension lever Z, througheye 75andpigtails 80, between valve stem and seat 91, through the eye ofneedle T and double looped through bed X and opening 104in tube 99. Thethread from bobbinAA also passes through opening 104 in tube 99 and bedX so that the end of thread M and the bobbin thread are above bed X.

If the operator presses forward on the treadle F, the sewing machinewill be operated in the nonnal manner. That is, pressing hard forwardlyand down on said treadle causes the sewing machine to run at top speedwhile letting up on said treadle causes the sewing machine to slow downand taking the foot off the treadle completely stops the sewing machinestopping the sewing action.

When the operator feeds the work piece across bed X beneath needle T andpresser foot U and heels down on treadle F raising link 1 pressing link4 against microswitches MS 01 and MS 2,- FIG. 3, tripping saidmicroswitches, microswitch MS 01 supplies current to points 45 and 50.Cam 40 rotates at the down position of needle T. By energizing point 45and' contact 44, the sewing machine will stop with needle T all thewayup while. energizing point 50 and contact 49, the sewing machine willstop with needle T all the way down.. Thus if point 45 and contact 44are energized, the sewing machine can be made to stop withneedle T up,since cam 40 willopen contact 44 from point 45 when said cam rotatesaround to that position breaking the electrical circuit.

If contact 49 engages point 50 they 1 supply current to the solenoidvalves D and 10 and relay R,. Said solenoid valves D and 10 passcompressed air to the positioning cylinder 24 by tube 25 and thebrake-cylinder 9 by tube 9a extending piston rod 23 which pulls cable 17rotating pulley 16 in a direction which moves rollers 53' against teeth56 of the slip clutch of FIGS. 8 and 9 against pulley 16 causing saidclutch to grab and thus rotate shaft 140 rotating in transmitter 14 andalso pulley 15, belt W and hand wheel- V causing cam 40 to rotate untilit opens contact 49 from point-50. At the-same time the needlepositioner, solenoid valves andrelay R are deenergized shifting pistonrod 23 into cylinder 24 andputting brake cylinder 9 in its brakeposition stoppinghand wheel V, opening the contacts 44 and 49, thusthe-brake of transmitter 14 is released and reappliedsvery quickly whilecontact 49 and point'50 are open. Needle vT is thus now positioned allthe way down through the work piece. Also at the same time when relay Rwas deenergized the normally closed contacts in said relay suppliedcurrent to solenoid Tvalve C passing air to cylinder 31 liftingpresser-foot S through rod 31a, lever 129, links 134 and 135 of FIG. 15,which allows the operator to tumthe work piece around the needle. Piston-rod 23 returnsinto cylinder 24through the slip action of the clutch inpulley 16.

Said slip clutch of' pulley 16is necessary to prevent the.

same and energizing contact 44 and point 45, solenoid valvesv D and 10and relay R thus the brake of transmitter 14 is released and piston rod23 pulls pulley 15 and the slip clutch of pulley 15 around so-thatneedle T is moved up. The brake of transmitter 14 isthenquicklyreapplied and solenoid valves A and 'B actuated releasingdisc c from disc 95d releasing thread M, moving pigtails 79 and 80 tothe left of FIG. Sdrawing thread M in recess-63, raising piston rodl09so that band 102 gives thread M and the bobbin thread a U-shaped bend asshown in FIG. 5 and then band 101 severs the threads from the work pieceautomatically. With microswitch 117 set in the needle up position,current is sent directly to valve l40which will open allowing air topass'through tube 166-to cylinder 139;"As the handwheel U is rotated bythe positioning cylinder 24, roller 144 will ride on ring 146 until itengages notch 145 at which time the needle T will be in top dead centerposition in which position the normal thread tensions of the sewingmachine are released to allow the thread M to be drawn freely from thesupply by the thread puller. Presser foot U remains in its up positionuntil the operator lets up on his heel on treadle F, at which time saidpresser foot drops. When piston rod 81 goes into cylinder 82 as far asallowed by screw 83, finger 70 activates microswitch 64 which energizesrelay R breaking the return line of the synchronizer solenoid 140 toreturn it to its normal position. Relay R is locked in the down positionby current from microswitch MS 02 and starts the return of piston rod 81to its position in FIG. 5 and at the same time activates piston rod 109and bands 101 and 102. When piston rod 81 reaches its position of FIG. 5it operates microswitches 65 and 65a, and piston rod 109 is lowered.Releasing microswitch 117, the foot lift solenoid valve C is energizedlifting presser foot U.

With the operator still pressing down with his heel on treadle F andholding microswitch 117 closed and then releasing said microswitch 117before cam 40 reaches and opens contact 44, piston rod 23 will turntransmitter shaft 14a and pulley 15 around to the down position ofneedle T before said needle stops and presser foot U is raised. Thisputs one stitch in the work piece at a time. Such operation requiredrequires a quick tap on knee plate 118 with the operators knee, while tocut the thread from the work piece as hereinbefore described requiresmicroswitch 117 to be held closed somewhat longer.

For greater speed in cutting the thread M from the work piece knee plate118 can be locked against microswitch 117 by pushing said knee plate allthe way down, see FIG. 18, rotating said knee plate against controlbutton 117a and raising said knee plate so that the hook on arm 118aengages pin 11%. Then the operator can at any time heel backward ontreadle F which activates piston rod 109 and thus bands 101 and 102,positioning the needle up, releases the tension on the thread, pulls thethread, trims the work piece and raises the presser foot. As long as thetreadle is heeled, the presser foot remains up permitting the removal ofthe finished work piece and the introduction of a new work piece.However, said microswitch must be released and opened by manually movingarm 1180 from pin 11% and said knee plate from control button 1170before the needle T down positioning elements as hereinbefore describedcan be operated.

When the operator presses forwardly or toes down hard on treadle F thesewing machine Q operates in the normal manner at top speed. Letting upon treadle F causes the sewing machine to slow down and taking the footoff of the treadle F completely stops the sewing machine.

Lever 87 is positioned between valve stem 90 and block 68 so thatmovement of said block to the entire right of FIG. 5 pushes said valvestem to the right against spring 89 releasing the thread M. However,when block 68 is to the left of FIG. 5, spring 89 returns said valvestem against seat 91 against thread M. At any time the operator canmanually pivot lever 87 to move either valve stem 90 or block 68 ifdesired.

Solenoid valves A, B, C, D and 10 are conventional electrically operatedvalves such as manufactured by the Automatic Switch Co., Florham Park,New Jersey, Catalog Nos. GY8314A33 and GY8314A51. Similarly regulators125, 126, 29, 24a and 127 are conventional air flow control valves.

The present invention is capable of considerable modifica tion and suchchanges thereto as come within the scope of the appended claims isdeemed a part thereof.

We claim:

1. In a sewing machine, a thread tensioning and releasing meanscomprising a pneumatic cylinder having an air inlet tube at one end, apiston rod slideably extending from said cylinder and fixedly connectedto said sewing machine, a flat member fixedly mounted on said sewingmachine, a second flat member carried by said cylinder facing said firstflat member, resilient means tending to retain said flat memberstogether with a sewing machine thread therebetween, pneumatic means forpulling the thread, and means for operating said cylinder moving saidsecond flat member away the first flat member and operating saidpneumatic means pulling said thread.

2. In a sewing machine, a thread tensioning and releasing meanscomprising a pair of opposed flat members for retaining a sewing machinethread therebetween, means for at times separating said flat members, apneumatic cylinder fixedly connected to said sewing machine, a pistonrod slideably extending from said cylinder, pigtails carried by saidpiston rod for receiving a thread therebetween, means for at timesoperating said first means and passing compressed air to said cylinderdrawing said piston rod therein and resilient means tending to move saidpiston rod from said cylinder.

3. In a sewing machine as claimed in claim 2, a tubular plug connectedto said sewing machine having a valve seat, a valve stem slideablymounted in said plug with a head facing said seat, resilient meanstending to hold said head against said seat with the sewing machinethread therebetween and a lever pivotally mounted on said sewing machineand positioned for at times being pivoted by said piston rod and pushingsaid valve stem against said resilient means and thus said head fromsaid seat.

1. In a sewing machine, a thread tensioning and releasing meanscomprising a pneumatic cylinder having an air inlet tube at one end, apiston rod slideably extending from said cylinder and fixedly connectedto said sewing machine, a flat member fixedly mounted on said sewingmachine, a second flat member carried by said cylinder facing said firstflat member, resilient means tending to retain said flat memberstogether with a sewing machine thread therebetween, pneumatic means forpulling the thread, and means for operating said cylinder moving saidsecond flat member away the first flat member and operating saidpneumatic means pulling said thread.
 2. In a sewing machine, a threadtensioning and releasing means comprising a pair of opposed flat membersfor retaining a sewing machine thread therebetween, means for at timesseparating said flat members, a pneumatic cylinder fixedly connected tosaid sewing machine, a piston rod slideably extending from saidcylinder, pigtails carried by said piston rod for receiving a threadtherebetween, means for at times operating said first means and passingcompressed air to said cylinder drawing said piston rod therein andresilient means tending to move said piston rod from said cylinder. 3.In a sewing machine as claimed in claim 2, a tubular plug connected tosaid sewing machine having a valve seat, a valve stem slideably mountedin said plug with a head facing said seat, resilient means tending tohold said head against said seat with the sewing machine threadtherebetween and a lever pivotally mounted on said sewing machine andpositioned for at times being pivoted by said piston rod and pushingsaid valve stem against said resilient means and thus said head fromsaid seat.